U.S. patent application number 09/737451 was filed with the patent office on 2002-06-20 for two line switch and power sharing for programmable means.
This patent application is currently assigned to Venstar, Inc.. Invention is credited to Bohm, Grant, Dushane, Steve, Zimmerman, Terry.
Application Number | 20020074865 09/737451 |
Document ID | / |
Family ID | 24963976 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020074865 |
Kind Code |
A1 |
Zimmerman, Terry ; et
al. |
June 20, 2002 |
Two line switch and power sharing for programmable means
Abstract
The present invention comprises means and methods for power
sharing for a lower voltage programmable means for operating a
switch which operates at a substantially higher voltage. The
present invention is preferably applied to two power line
thermostat control of HVAC equipment. Although a programmable
thermostat is described in the specific description of the
invention as the programmable means, it is intended that the
present invention be applicable to other such devices where power
is stored by capacitance or in rechargeable batteries for use by
lower voltage programmable means while at the same time permitting
sufficient current flow through a substantially higher power switch
to operate directly or indirectly electrical power equipment.
Inventors: |
Zimmerman, Terry;
(Northridge, CA) ; Dushane, Steve; (Granada Hills,
CA) ; Bohm, Grant; (Reseda, CA) |
Correspondence
Address: |
David T. Bracken
The Law Office of David T. Bracken
4839 East Bond Avenue
Orange
CA
92869
US
|
Assignee: |
Venstar, Inc.
|
Family ID: |
24963976 |
Appl. No.: |
09/737451 |
Filed: |
December 14, 2000 |
Current U.S.
Class: |
307/125 |
Current CPC
Class: |
H02M 1/0006 20210501;
H02M 5/2573 20130101; H02J 7/00 20130101 |
Class at
Publication: |
307/125 |
International
Class: |
H02J 009/00 |
Claims
1. A process for sharing power to a lower voltage programmable
means for controlling a substantially higher voltage switch means
for turning on and off electrical equipment comprising: (a) two
power lines connected with an alternating current source at the
substantially higher voltage such that, upon completion of a power
circuit between the two power lines, the electrical equipment
operates; (b) a bridge rectifier connected between the two power
lines at two AC connections of the rectifier, the bridge rectifier
further connected at one of its DC terminals to a common ground;
(c) a field effect transistor connected at its drain to the second
of the DC connections of the rectifier, a source of the field
effect transistor connected to a common ground and a gate of the
field effect transistor connected to a programmable means adapted
to activate and deactivate the field effect transistor to
respectively complete or break the power circuit; (d) power storage
means for storing power from the alternating current source and
supplying temporarily the power needs of the programmable means;
(e) voltage regulation means connected with the programmable means
for reducing the substantially higher voltage to the lower voltage
for use by the programmable means, the voltage regulation means
further connected with the power storage means such that power is
directed from the power storage means to the programmable means;
(f) the programmable means sensing a change making desirable
operating of the electrical equipment, the programmable means then
activating the field effect transistor to complete the power
circuit and turn on the electrical equipment; (g) deactivating and
then reactivating the field effect transistor during which time
charge is stored in the power storage means from the alternating
current source but the electrical equipment continues to
operate.
2. The process of claim 1 wherein programmable means comprises
means for sensing alternating current across the rectifier, whereby
programmable means selects the
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to power sharing or "power
stealing" for lower voltage control means concurrent with powering
a local substantially higher voltage switch.
[0002] The prior art has demonstrated certain solutions to the
problem of providing lower voltage and current thermostat control
means on the same circuit as a substantially higher voltage and
current switch which in turn activates HVAC equipment by direct
line connection or by relay.
[0003] Means for relay line voltage (typically at about 24 vac)
powering of the control means are described in U.S. Pat. No.
4078720 and 5903139. U.S. Pat. No. 4,078,720 describes a time
variable set point thermostat adapted for use in a two-wire circuit
of a heating or cooling system. Electric timer means are connected
with a thermostat switch and starting relay means of a transformer
having a primary and secondary winding periodically changing the
set point of the thermostatic switch at selected intervals. The
circuit is arranged to limit the current in the two-wire control
circuit to a value less than that required to actuate the starting
relay of the heating or cooling system in the two-wire control
circuit with the thermostat switch open and to actuate the starting
relay when the thermostat switch is closed when the ambient
temperature to be regulated varies a determined amount from a
selected temperature set point and the thermostatic switch is
closed.
[0004] U.S. Pat. No. 5,903,139 describes a more sophisticated
method of providing a zero point zone "stealing" of power so that
enough power is taken for storage in high and low voltage
capacitors while at the same time maintaining residual power
passing to the relay to have continuous operation of heating
equipment. A pair of power FETs are connected to the series power
terminals, and the gates are controlled by logic and phase timers.
FETs are turned off at the end of a phase, while a small amount of
power sufficient to operate the control and circuitry is diverted
to a power storage circuit, then the FETs are turned back without
substantial interruption to the load. One embodiment uses a
bi-directional charge pump to transfer power between low- and
high-voltage power storage circuits. The circuit can operate with
symmetrical or nonsymetrical AC or DC loads. It is significant for
the concept of this patent that relatively precise timing of the
zone about the zero point be predicted so that the "stealing" take
place in the very low voltage zones of the continuous voltage curve
so as not to cause the relay to be underpowered. The several
circuit pieces required to achieve the described result in the
patent are subject to failure or off specification operation,
thereby increasing the likelihood that the patent device will fail
or have a degraded performance. For instance, there are two sets of
latches and phase timers critical to operation of the device, in
addition to the two back to back FET's whose cooperative operation
is critical to the switching function.
[0005] A line voltage solution is described in U.S. Pat. No.
4,776,514 and 5,635,896. U.S. Pat. No. 4,776,514 describes a two
wire line voltage thermostat with first and second terminals for
receiving line voltage power and for connection to a load, a
transformer having a current primary winding, a voltage primary
winding and a secondary winding, a primary controller connecting
the current and voltage primary windings to the terminals, the
controller having at least first and second states, the controller
in the first state energizing both the current and voltage primary
windings and in the second state energizing only the current
primary winding, and a temperature responsive circuit connected to
the secondary winding for controlling the controller between the
first and second states in accordance with sensed temperature such
that the load can be energized when the controller is in one of the
states and can be deenergized when the controller is in the other
of the states. Other prior art describe the unfavorable effect of
having transformers associated with the thermostat in terms of
increased heat generation, size and cost.
[0006] U.S. Pat. No. 5,635,896 describes a communication system
with a remote switching module having two signal terminals
connected by just two conductors to the signal terminals of a local
decoding module. Power is directly provided only to the local
decoding module, which applies DC voltage of a first level across
the conductors. The remote switching module has a voltage regulator
which provides power of a second voltage level lower than the first
level for operating a control unit in the switching module. The
control unit controls a variable impedance having higher and lower
impedance levels and which is connected across the switching
module's signal terminals. The decoding module can detect the
different impedance levels by sensing the current flow on the
conductors. The switching module communicates with the decoding
module by modulating the time intervals between changes in
impedance levels. It is clearly disadvantageous to require of two
separated modules which results increased installation, manufacture
and troubleshooting costs.
SUMMARY OF THE INVENTION
[0007] The present invention comprises means and methods for power
sharing for a lower voltage programmable means for operating a
switch which operates at a substantially higher voltage. The
present invention is preferably applied to two power line
thermostat control of HVAC equipment. Although a programmable
thermostat is described in the specific description of the
invention as the programmable means, it is intended that the
present invention be applicable to other such devices where power
is stored by capacitance or in rechargeable batteries for use by
lower voltage programmable means while at the same time permitting
sufficient current flow through a substantially higher power switch
to operate directly or indirectly electrical power equipment. The
present invention may be used in the presence of more than two
power lines to accomplish HVAC equipment operating, the additional
lines being used for other functions.
[0008] The present invention is a dramatic simplification of the
overly populated circuit of U.S. Pat. No. 5,903,139. The present
invention connects the two power lines described above (connected
to a low voltage relay or to line voltage) to a bridge rectifier,
the output connections of which are connected to a common through
the drain and source of an FET. The gate of the FET is activated by
a signal from the programmable means, which then causes the current
to flow (switches on) through the two power lines to power the
relay or directly power the HVAC equipment. The drain of the FET is
also connected with power storage means, voltage regulation means
and the programmable means. The additional connected means function
so that, when the HVAC equipment is operating by FET gate
activation, the FET for a very short interval operates to stop
current through the source and drain, thereby stopping current flow
for a very short interval to the HVAC equipment, thereby delivering
DC voltage and current to the power storage means, voltage
regulation means and the programmable means. The programmable means
preferably operate on power from the power storage means, so that
when the HVAC equipment is operating the power storage means are
being depleted of power by the programmable means, requiring
recharging of the power storage means by shutting off the power to
the HVAC equipment for a very short interval so that the power
storage means are recharged at least in part.
[0009] It is preferable to provide sensing means so that the
programmable means may determine an appropriate portion of the
alternating current curve from which to take its very short
interval of power sharing. The present invention preferably obtains
a short and timed portion of DC power from the AC power line inputs
substantially after the AC voltage curve rises above or below zero
but substantially before the maximum positive or negative voltage
is reached.
[0010] It is also preferable that when the HVAC equipment is shut
off, i.e., the programmable means deactivates the FET so that no
current flows to the HVAC equipment directly or indirectly, the
power from the two power lines is directly usable by the
programming means through a voltage regulation means.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic and block diagram of the invention in
its simplest form.
[0012] FIG. 2 is a complete schematic diagram of a specific
embodiment of the invention comprising a programmable thermostat as
the programmable means together with power storage means and
voltage regulation means.
[0013] FIG. 3 is a graph of voltage across the bridge rectifier
when the HVAC is required to be operating.
[0014] FIG. 4 is a graph of voltage across the FET when the HVAC is
required to be operating.
[0015] FIG. 5 is a graph of voltage to the voltage storage means
when the HVAC is required to be operating and power is being
shared.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The invention is now discussed with reference to the
Figures.
[0017] FIG. 1 shows two power lines 1 and 7 connected with
rectifier D1-D4 at the AC input terminals. The DC output terminals
100 and 101 are respectively connected with a common ground
(corresponding to connection 5 of the JP1 HEADER of FIG. 2) and the
drain of FET Q1, the source of which is connected with the common
ground. Bridge rectifier D1-D4 preferably comprised of Schottkey
barrier diodes for quick response as required by the objects of
this invention.
[0018] It is preferable that connections (not shown in FIG. 1) be
made to the AC connections of rectifier D1-D4 to input to the
programmable means the continuous voltage changes of the power
lines during "on" periods of the HVAC equipment. The programmable
means then may cause FET Q1 to deactivate and reactivate current
flow in this process of power sharing with the HVAC equipment. It
is well known that power supply in the common 24/120/240 vac
comprises substantial and measurable "noise" in the form of voltage
spikes and drops and that relays for and HVAC equipment itself is
designed to continue operating irrespective of this line "noise".
The skilled person is thus informed with this disclosure that the
power sharing intervals of the present invention may be as long as
the longest permissible power drop which the relay for or HVAC
equipment itself will experience as negligible "noise" without
affecting the operation of the HVAC equipment. The interval is
preferably chosen from a zone of about 20% to 80% of maximum
positive or negative voltage in the alternating power line voltage.
In such an interval range, the present invention is clearly
distinguished from the preferred interval of U.S. Pat. No.
5,903,139 about the zero point. In the typical 50-60 Hz current
supplied to residential and many commercial users, a half cycle is
about 0.0083 seconds, the sharing period of which is preferably
about 10-20% of the half cycle time before peak voltage.
[0019] FIG. 1 shows that the gate of FET Q1 is connected to
programmable means 103, while its drain is connected to power
storage and voltage regulation means 102. It will be understood by
inspection of FIG. 2 and this description that means 102 and 103
are effectively connected for cooperative action according to the
objects of the invention.
[0020] FIG. 2 is a specific example of the present invention
whereby many of the circuit elements and operations are in IC U3, a
part of the programmable means. In FIG. 2, the two power lines 1
and 7 are shown connecting with the invention devices at the header
JP1, and, as in FIG. 1, rectifier D1-D4 is connected at its AC
inputs to the lines 1 and 7 and FET Q1 is connected at its drain to
the positive DC connection of rectifier D1-D4. Lines 1 and 7 are
respectively connected to diodes D8 and D9 to provide power line
voltage sensing connections with IC U3. Thus the programmable means
receive continuous inputs on the voltage of the power lines 1 and 7
so that an appropriate shut off interval may be applied when the
invention switch is in the "on" mode.
[0021] The drain of FET Q1 is connected through diode D5 to power
storage capacitor C2. It is capacitor C2 which charges to capacity
without restriction when the invention switch is in the "off" mode
and receives the DC charge during the short intervals when the
power line current is shut off when the invention switch is in the
"on" mode. The prgrogrammable means draw power from capacitor C2
for their operation when power line power is not directly
available, i.e., the invention switch is in the "on" mode. Other
functions of the programmable means are more fully described in
U.S. Pat. No. 6,134,134 to Dushane et al, including temperature
sensing and response with various modes of operation of HVAC
equipment as appropriate with a two line thermostat.
[0022] Voltage regulation means 104 are shown in FIG. 2 as
comprising several circuit elements connected to the logic means
for providing power thereto from the voltage storage means (in the
case of FIG. 2, from the capacitor C2). It will be within the
ability of the skilled person to adapt these elements so that
inputs 1 and 7 may be operated at line voltage or reduced voltage
as is described above. Voltage sensing input means 105 in FIG. 2
shows that the programmable means optionally includes voltage
sensing input means 105 (as in FIG. 2) with which to sense the
voltage across rectifier D1-D4 when the FET is activated in the
"on" mode. Voltage sensing input means 105 has connections 106 as
in FIG. 1 so that the programmable means detects voltage levels
across rectifier D1-D4 such that FET Q1 is switched on and off at
times appropriate to achieve the objects of the invention. cm We
claim:
* * * * *